Environment

A green process for extracting gold

Stephen Foley holds a vial of the environmentally-friendly solution that his team has developed to extract gold from scrap electronics
Stephen Foley holds a vial of the environmentally-friendly solution that his team has developed to extract gold from scrap electronics
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Stephen Foley holds a vial of the environmentally-friendly solution that his team has developed to extract gold from scrap electronics
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Stephen Foley holds a vial of the environmentally-friendly solution that his team has developed to extract gold from scrap electronics

A research team at the University of Saskatchewan has found what may be an inexpensive and environmentally-friendly way of recycling gold from jewelry and electronics. Using a solution of what is essentially reusable table vinegar, the team has shown that for CAD$66 (about US$47) it can produce one kilogram (2.2 lb) of gold with 100 liters (26 gal) of reusable waste water – this is as compared to current methods that can cost over CAD$1,500 (US$1,070) and create 5,000 liters (1,321 gal) of toxic, non-reusable waste.

According to Stephen Foley, associate professor in the Department of Chemistry and leader of the project, 80 percent of the 50 million tons (4.5 million tonnes) of e-waste produced globally each year ends up in landfills, and seriously impacts the environment and surrounding populations as a result.

The problem with gold is that it's one of the least reactive chemical elements on the planet, which makes it difficult to dissolve. Thus current industry standard methods to remove it from scrap electronics rely on either highly-toxic cyanide solutions that are non-recyclable, or use high heat to burn off the gold, releasing dangerous gases into the air in the process.

The method created by Foley and his team is meant to eventually replace both of those approaches with a less expensive, non-toxic, recyclable solution.

"We use one of the most mass-produced chemicals, acetic acid, at five per cent concentra­tion; it's plain table vinegar," explains Foley. "We use a minute amount of an acid and an oxidant to finish our solution."

Foley points out that the solution developed by his team is the greenest solvent next to water, so it eliminates the vast number of environmental concerns that come with the other long-standing methods of gold extraction.

The next step for the scientists is to identify industry partners who can help them move the process into very large-scale applications for gold recycling from gold-bearing materials. Foley believes that the method could also eventually be used in gold mining, which currently relies on toxic sodium cyanide for extraction.

Over the last several years, research teams elsewhere have developed other solutions for eliminating or reducing the environmental impact of gold mining. These include one utilizing corn starch, another that extracts gold from sewage, and another that involves a mercury recapture system.

Source: University of Saskatchewan

10 comments
Gavin Roe
hope it works out guys
Fretting Freddy the Ferret pressing the Fret
This is one of the many steps we need to make if we want this planet to be habitable for future generations.
Expanded Viewpoint
So why isn't the process detailed here? Years ago I heard about some guy who supposedly had a new process for gold extraction from gold bearing soils, and he got some people interested in it, then raised a bunch of bucks and even got a "pilot plant" built, and the "process" itself was chemically impossible!! So the investors got burned, the guy ran off to who knows where, and only the contractor who built the pilot plant came out ahead in the deal. Had any of the investors taken the time to consult with someone with a degree in chemistry to see if the process was valid or not, they could have avoided being ripped off and the fraudster could have been put in jail for running a scam. Gold being the nearest thing to an inert substance we have save for the noble gasses, is not so easy to latch on to. It takes a LOT of energy in every form of collection/extraction you may care to name to get that stuff, be it just human labor or running a huge mine. So I say "Show us the process!!" or shut up.
ADVENTUREMUFFINffin
Good "solution" (NPI) if the rate of extraction is feasible...
Douglas Bennett Rogers
It is hard to tell what this is. I'm guessing the acetic acid dissolves the epoxy, since that's what it does. The gold is already metallic so it doesn't need to be extracted from ore. The cyanide would be used for this. Heat would separate glass, plastic, and metals from the gold. Reactants can always be separated and cleaned but this is a matter of economics.
David A Galler
This is interesting that in this day and age there are still things to be discovered in simple chemistry.
Esteban Sperber Frankel
I new allways that to polish gold with acetic acid.
Don Duncan
Expanded Viewpoint: What % of new "get rich quick" ideas pan out? Few. How many are scams? How can we know if the promoter was just wrong, or a fraud? I say no one should go to jail based solely on failure. If clear fraud, not overzealous exuberance, can be proven, then sure, jail. But there is "due diligence" that should be exercised. The investor has a responsibility also. He may be lazy, and a dreamer, the result being a loss. It shouldn't be assumed all the blame can be laid at the foot of the promoter. Usually there is plenty to go around. I once tried to talk someone out of investing in a risky venture, one which I evaluated to be a 99% possible scam. As I explained my reasons in front of both parties, being brutally frank, the investor who was going to put up all his wealth, threatened to punch me out if I continued. I laughed. I almost called him a damn fool, but I could see he was not joking, red in the face, and ready to attack. I backed off. He invested and was picked clean. He blamed me.
Galane
Step 1. Run junk electronics through a BlendTec blender to pulverize and expose the precious metals as much as possible. Don't breath this!
joshua62
saw a video on this , hiding details of how to do it. if its all about being green why are they charging for the details . it kinda defeats the purpose of trying to be green if the only ones who can use it has to pay for the details. if its free info you do a lot of good and deserve some credit. but if your gunna charge for it you aint helpin anything and they don't deserve any prays
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